Astragalus speirocarpus

Plants somewhat slender, 20–45 cm, strigulose; from superficial caudex. Stems ascending or diffuse, strigulose. Leaves 1.5–7.5 cm; stipules (1–)1.5–4(–5), papery at proximal nodes; leaflets 7–17(–21), blades cuneate-oblanceolate, oblong, or cuneate-obcordate, 2–10(–12) mm, apex truncate to deeply retuse, surfaces strigulose, sometimes adaxially glabrescent. Peduncles erect or incurved-ascending, (1–)2.5–5(–6.5) cm. Racemes (3–)7–17(–20)-flowered; axis 1–3.5(–5) cm in fruit; bracts 1–2.5 mm; bracteoles 2. Pedicels 1–2.5 mm. Flowers 14.7–20 mm; calyx 5.2–8(–9.1) mm, villosulous, tube 4.7–7.3 mm, not swollen or gibbous proximally, marcescent, lobes triangular, 0.5–1.2 mm; corolla whitish or tinted lilac, keel tip maculate; keel 10.6–13(–14.5) mm. Legumes pendulous, green or slightly mottled, becoming brown or stramineous, coiled through flat 1.25–2.5 spirals, or elaborately and irregularly contorted, linear-oblong, laterally compressed, 9–14 × (2.7–)3.2–5(–6) mm, stiffly leathery or subligneous, strigulose; stipe (4–)5–11 mm. Seeds (14–)20–28(–30). 2n = 22.

Phenology: Flowering May–Jul.
Habitat: Dry hillsides and valleys, stony or sandy substrates over basalt, in sagebrush scabland.
Elevation: 200–800 m.

Wash.

Discussion

Astragalus speirocarpus is locally abundant along the Columbia and Yakima river valleys in Kittitas and Yakima counties, southward to eastern Klickitat and western Benton counties.

The coiled or contorted fruits, diagnostic for the medick milkvetch, suggest the common name by their gross resemblance to the much smaller fruits of Medicago.

Selected References

None.

Lower Taxa